Apparatus and method for removing stenotic material from stents

ABSTRACT

Apparatus and methods are provided for recanalizing stented regions within the vasculature which have become restenosed. A shearing body is displaced within the stented region in order to dislodge the stenotic material from an interface envelope defined by the inner surface of the stent. Usually, the shearing body will be compliant and sized slightly larger than the stent in order to remove stenotic material substantially uniformly around the entire interface envelope. The shearing body may be in the form of a brush, helical row, spaced-apart disks, solid compressible body, or a variety of other specific configurations.

This is a division of U.S. application Ser. No. 08/798,722, filed Feb.12, 1997, the full disclosure of which is incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to apparatus and methods forremoving occluding material from stented regions within blood vesselswhich have restenosed. More particularly, the present invention relatesto apparatus and methods for shearing the occluding material from aroundan interface envelope defined by the stent.

Percutaneous transluminal angioplasty (PTA) procedures are widely usedfor treating stenotic atherosclerotic regions of a patient's vasculatureto restore adequate blood flow. Catheters having an expansible distalend, usually in the form of an inflatable balloon, are positioned in anartery, for example a coronary artery, at a stenotic site. Theexpansible end is then expanded to dilate the artery in order to restoreadequate blood flow to regions beyond the stenosis. While PTA has gainedwide acceptance, it suffers from two major problems: abrupt closure andrestenosis.

Abrupt closure refers to rapid reocclusion of the vessel within hours ofthe initial treatment, and often occurs in patients who have recentlysuffered acute myocardial infarction. Abrupt closure often results fromrapid thrombus formation which occurs in response to injury of thevascular wall from the initial PTA procedure. Restenosis refers to are-narrowing of the artery over the weeks or months following an initialapparently successful PTA procedure. Restenosis occurs in up to 50% ofall PTA patients and results at least in part from smooth muscle cellproliferation and migration.

Many different strategies have been proposed to ameliorate abruptclosure and reduce the restenosis rate. Of particular interest to thepresent invention, the implantation of vascular stents following PTA hasbecome widespread. Stents are thin-walled tubular scaffolds which areexpanded in the arterial lumen following the PTA procedure. Mostcommonly, the stents are formed from a malleable material, such asstainless steel, and are expanded in situ using a balloon.Alternatively, the stents may be formed from a shape memory alloy orother elastic material, in which case they are delivered in a radiallyconstrained configuration and allowed to self-expand at the PTAtreatment site. In either case, the stent acts as a mechanical supportfor the arterial wall, inhibiting both abrupt closure and restenosis.

While stents have been very successful in inhibiting abrupt closure andreasonably successful in inhibiting restenosis, a significant portion ofthe treated patient population still experiences restenosis over time.Most stent structures comprise an open lattice, typically in a diamondor a spiral pattern, and cell proliferation (often referred to ashyperplasia) can incur in the interstices between the support elementsof the lattice. As a result, instead of forming a barrier to hyperplasiaand restenosis, the stent can become embedded within an accumulated massof thrombus and tissue growth, and the treatment site once again becomesoccluded.

To date, proposed treatments for restenosis within previously stentedregions of the coronary and other arteries have included both follow-upballoon angioplasty and directional atherectomy, e.g. using the Simpsonatherectomy catheter available from Guidant Corporation, Sunnyvale,Calif. Neither approach has been wholly successful. Balloon angioplastycan temporarily open the arterial lumen, but rarely provides long-termpatency. Directional atherectomy can successfully debulk the lumenwithin the stent, but rarely removes the material in a symmetricpattern. Moreover, it has been found that the atherectomy cutting bladescan damage the stent, leaving protruding metallic pieces in the bloodvessel lumen. Such discontinuities can act as sites for further thrombusformation.

For these reasons, it would be desirable to provide improved methods fortreating restenosis within regions of the vasculature which havepreviously been implanted with stents. More particularly, it would bedesirable to provide apparatus and methods for removing stenoticmaterial from within the stents in a uniform and symmetric manner toprovide a recanalized vascular lumen which is less likely to suffer fromfurther restenosis. The apparatus and methods will preferably be capableof both dislodging the stenotic material and subsequently capturing andremoving the dislodged material from the blood vessel lumen. Desirably,the apparatus will be able to dislodge and remove the stenotic materialfrom along an interface envelope which is defined by the stent which hasbecome embedded within the stenotic material. Removal will preferably beeffected in a short amount of time, preferably using only a single orlimited number of passes through the restenosed region within the stent.The apparatus and methods will be relatively easy to implement, presentacceptable risks to the patient, and be readily performed by physicianswho are familiar with balloon angioplasty and other conventionalintravascular treatments. At least some of these objectives will be metby the various aspects of the present invention described below.

2. Description of the Background Art

Post-angioplasty restenosis is discussed in the following publications:Khanolkar (1996) Indian Heart J. 48:281-282; Ghannem et al. (1996) Ann.Cardiol. Angeiol. 45:287-290; Macander et al. (1994) Cathet. Cardiovasc.Diagn. 32:125-131; Strauss et al. (1992) J. Am. Coll. Cardiol.20:1465-1473; Bowerman et al. (1991) Cathet. Cardiovasc. Diagn.24:248-251; Moris et al. (1996) Am. Heart. J. 131:834-836; Schomig etal. (1994) J. Am. Coll. Cardiol. 23:1053-1060; Haude et al., "Treatmentof In-Stent Restenosis," in Endoluminal Stenting 1996, Chapter 52, pages357-365; Gordon et al. (1993) J. Am. Coll. Cardiol. 21:1166-1174; andBaim et al. (1993) Am. J. Cardiol. 71:364-366. These publicationsinclude descriptions of follow-up angioplasty and atherectomy aspossible treatments for restenosis.

Thrombectomy and atherectomy catheters having rotating brush andfilament structures are described in U.S. Pat. Nos. 5,578,018;5,535,756; 5,427,115; 5,370,653; 5,009,659; and 4,850,957; WO 95/29626;DE 39 21 071 C2; and Netherlands 9400027.

Representative atherectomy catheters are described in U.S. Pat. Nos.4,273,128; 4,445,509; 4,653,496; 4,696,667; 4,706,671; 4,728,319;4,732,154; 4,762,130; 4,790,812; 4,819,634; 4,842,579; 4,857,045;4,857,046; 4,867,156; 4,883,458; 4,886,061; 4,890,611; 4,894,051;4,895,560; 4,926,858; 4,966,604; 4,979,939; 4,979,951; 5,011,488;5,011,489; 5,011,490; 5,041,082; 5,047,040; 5,071,424; 5,078,723;5,085,662; 5,087,265; 5,116,352; 5,135,483; 5,154,724; 5,158,564;5,160,342; 5,176,693; 5,192,291; 5,195,954; 5,196,024; 5,209,749;5,217,474; 5,224,945; 5,234,451; 5,269,751; 5,308,354; 5,314,438;5,318,576; 5,320,634; 5,334,211; 5,356,418; 5,360,432; 5,376,100;5,402,790; 5,443,443; 5,490,859; 5,527,326; 5,540,707; 5,556,405;5,556,408; and 5,554,163.

SUMMARY OF THE INVENTION

The present invention provides apparatus and methods for removingstenotic material from within previously stented regions of a patient'svasculature. The present invention is particularly intended for treatingregions of restenosis within the stent which result from theaccumulation of cellular, thrombotic, and other material over the weeksand months following an initially successful stent placement. Thepresent invention will also be useful for treating relatively rapidthrombus formation which may sometimes occur during the hours and daysimmediately following a stent placement procedure.

Methods according to the present invention comprise displacing ashearing body within a stented region within a blood vessel, usually acoronary or other artery, which has become restenosed or otherwiseoccluded following the initial stent placement. The shearing body may beaxially translated and/or rotated within the stented region, usuallybeing rotated while it is simultaneously translated in order to effect auniform shearing action over an interface envelope defined by the stentwithin an accumulation of occluding material. The shearing body willpreferably have a width which is sufficient to engage substantially theentire periphery of the stent interface envelope as the shearing body isdisplaced therein. Usually, the shearing body will be compliant andslightly over-sized so that it engages and sweeps the entire interfaceenvelope as it is displaced therein. Alternatively, or additionally, thewidth of the shearing body may be selectively adjusted so that itconforms to the size of the stent interface, again typically beingadjusted so that it is slightly oversized and compliant against theinterface envelope. Thus, the present invention relies at least in parton the stent itself to define the region which is to be recanalizedwithin the blood vessel.

The methods of the present invention will optionally further comprisecollecting and removing the dislodged stenotic material from the bloodvessel. Collection and removal will most often be accomplished using thesame catheter or catheter assembly which carries the shearing body,typically by aspiration, entrapment, filtering, or some combinationthereof. It will be appreciated that various catheter assemblies can beput together using coaxially arranged components which may be introducedthrough a single vascular access site, typically a femoral access tract.Alternatively, collection and removal may be accomplished using separatecollection apparatus, such as a catheter or catheter assembly, which isintroduced through a separate access point. The separate catheter orcatheter assembly would rely on similar collection capabilities, such asaspiration, filtering, entrapment, or the like, and will typically belocated on the side of the stenosed region opposite to that from whichthe shearing body is accessed. In some instances, it may be desirable topartially or totally isolate the stented region from circulation duringrecanalization. For example, embolic filters may be placed upstream anddownstream of the stented region. Alternatively, spaced-apart balloonsmay be used to fully isolate the isolated region, although suchisolation should not be performed for an extended time period which canresult in ischemia.

As stated above, the shearing body is preferably compliant and will havea width (diameter in the case of circular cross-sections) which is atleast slightly greater than the interior width or diameter of theinterface envelope created by the stent. Typically, the shearing bodywill be selected to have a width which is from 1% to 25% greater thanthat of the interior width or diameter of the interface envelope,preferably being from 2% to 20% greater, and more preferably being from5% to 15% greater. Most often, the shearing body will have a generallyround cross-section, and the width will be equal to the diameter. Thecross-section, however, need not be circular, and in some instances itmay be desirable to provide a polygonal cross-section, an irregularcross-section, a cross-section having surface texture such as ribs orprotrusions, or the like.

The shearing body will have an exterior surface or region capable ofdislodging stenotic material at the stent interface envelope as theshearing body is displaced therein. In particular, the exterior surfacewill include features, elements, texturing, or the like which will shearand/or abrade the stenotic material over the interface envelope definedby the interior of the stent as the shearing body is displaced therein.

For example, the shearing body may be a brush having a plurality ofradially disposed filaments, where the distal tip of each filament canact to abrade stenotic material from within the stent interface envelopeas the brush is rotated and/or axially translated. In a preferred aspectof the present invention, the brush comprises a helical row offilaments, usually being tapered with a small diameter at the end whichfirst enters the stented region to be treated. Alternatively, a brushstructure could comprise a series of spaced-apart disk, axially alignedrows, or other non-continuous structures. The use of brushes havingrelatively large openings between filament structures is advantageousand permits the stenotic material to be accumulated with these voids.Thus, the material may be trapped within the shearing body itself as theshearing body is contained and removed from the blood vessel. Thefilaments can be composed of polymeric materials, e.g. polyethylenes,polyethyleneterephthalates, polypropylenes, polyimides, polyamides(nylons), and copolymers thereof, or can be composed of metals, e.g.stainless steel, nickel-titanium alloys (nitinols), titanium alloys,cobalt alloys, and the like. The brushes may be formed from filaments ofa single material or may be formed from individual filaments composed oftwo or more different materials. The individual filaments themselves maybe formed from more than one material, e.g. polymeric coated metalwires, or the like.

A variety of other particular structures for the shearing body are alsopossible. For example, the shearing body may comprise one or morecontinuous webs of materials (e.g. fabrics, membranes, or the like)which are arranged to project radially outward to define the shearingbody. The webs may be formed from natural or synthetic materials orfibers, usually being synthetic polymers, such as polyethylenes,polyethyleneterephthalates, polypropylenes, polyimides, polyamides(nylons), polyurethanes, latex, silicone, rubber, and copolymers andmixtures thereof. Fabrics may be formed by weaving different fiberstogether, and may optionally be reinforced using metal fibers orfilaments, where the metals may be any of the materials described abovefor use as brush filaments. Such continuous webs may be arranged as acontinuous helical row, as a series of spaced-apart disks, or in avariety of other specific configurations. In many ways, the use ofcontinuous webs of material will be analogous to the use of brushfilaments arranged in helical or disk-like patterns. Rotation andtranslation of such shearing bodies will act both to dislodge thestenotic material and entrap the dislodged material within voids presentbetween successive turns or disks of the web.

As yet another alternative, the shearing body may comprise a cage orsimilar lattice structure comprising individual elements which act toshear the stenotic material as the shearing body is rotated and/oraxially translated through the stented region being treated. Usually,but not necessarily, the cage structures will be selectively expandableso that the user can adjust the width or diameter in situ. Most often,the axial length of the cage structure will be adjustable so that theradius can be increased and/or decreased. The cage structure willusually be compliant so that it will be slightly compressed against theinterface envelope of the stent as it is displaced therein. An advantageof the use of such cage structures is that the removed stenotic materialmay be at least partially entrapped within the cage, facilitatingremoval of the material from the vasculature. The cage structures may befabricated from a variety of materials, including both metals andpolymers, and the materials may be selected so that they are softer thanthe stent to reduce the likelihood that the stent will be damaged duringthe removal process.

In a preferred aspect of the method of the present invention, a catheteris positioned on one side of the stented region. The shearing body ispositioned on the opposite side of the stent and then translated throughthe stented region toward the distal end of the catheter to dislodgestenotic material from the interface envelope defined by the stent. Thedislodged stenotic material is typically aspirated or otherwisecollected into the distal end of the catheter. Usually, but notnecessarily, the shearing body will be deployed from the same catheteror catheter assembly which is used to aspirate or otherwise collect thedislodged stenotic material. For example, the catheter may first bepositioned on one side of the stented region, the shearing body passedthough the stented region in a collapsed or non-deployed configuration,and the shearing body then deployed on the opposite side of the stentedregion from the catheter. The deployed shearing body may then be drawnproximally back toward the catheter or catheter assembly with thedislodged material being aspirated into such catheter or catheterassembly. Deployment may comprise releasing the shearing body fromradial constraint. Alternatively, deployment may comprise actively andselectively increasing the diameter of the shearing body, such as a cagestructure, by the techniques described above. Also as described above,separately introduced catheters or catheter assemblies may be used foraspiration/collection and for shearing body deployment.

In yet another aspect of the present invention, the method ischaracterized by use of a shearing body having a cross-sectionalgeometry which is sufficiently large to engage in the entire interiorsurface of the stent when the shearing body is displaced therein. Use ofsuch a shearing body results in substantially uniform displacement anddislodgement of the stenotic material from the interface envelopedefined by the stent.

In yet another particular aspect of the present invention, the method ischaracterized by rotation and translation of the compliant shearing bodythrough the stented region, wherein at least a portion of the compliantshearing body has a width which is greater than the diameter of thestent so that the shearing body is compressed by the stent as it passestherethrough.

In still yet another specific aspect of the present invention, themethod is characterized by rotating and translating a tapered shearingbody through the stented region, where a small width end of the taperedshearing body enters the stented region first.

In a still further specific aspect of the present invention, the methodis characterized by rotation and translation of a brush assembly throughthe stenosed stented region being treated.

In one more specific aspect of the present invention, the method ischaracterized by rotation and translation of a helical shearing bodythrough the stented region.

Apparatus according to the present invention include catheters, cathetersystems, and catheter kits which are specially intended and adapted forperforming the methods described above. In particular, the apparatus aredesigned to afford percutaneous intravascular placement of the shearingbody at the site of restenosis within a previously stented region of thevasculature. To that end, catheter systems according to the presentinvention may comprise an inner catheter shaft having a proximal end anda distal end. The shearing body, usually being radially compressible, isdisposed near the distal end of the catheter shaft, and a sheath isslidably coupled to the inner catheter. The sheath has a cavity near itsdistal end, where the cavity receives the shearing body to effect radialconstraint and containment. The shearing body may have any of thestructures described above. The catheter system will usually furtherinclude an outer catheter tube having a proximal end, a distal end, anda inner lumen. The outer catheter tube will usually have an aspirationport near its proximal end so that dislodged stenotic material can beaspirated from the vasculature. This catheter system is particularlysuited for introducing the shearing body in its radially collapsedconfiguration through the stented region to a side of the stented regionopposite to the location of the catheter. The shearing body is thenreleased from the sheath, and the deployed shearing body drawn backtoward the catheter to dislodge the stenotic material as generallydescribed above. The dislodged material may then be aspirated throughthe outer catheter tube.

Preferably, the inner catheter shaft of the catheter system will have aguidewire lumen extending therethrough. The guidewire lumen is usefulfor positioning the catheter system over a guidewire in a conventionalmanner. The inner catheter shaft usually has a diameter in the rangefrom about 0.2 mm to 1 mm, more usually from 0.3 mm to 0.6 mm. Theshearing body has a maximum width when radially unconstrained in therange from 2 mm to 5 mm, preferably from 3 mm to 4 mm. The sheath cavityhas a diameter in the range from 0.5 mm to 2 mm, usually from 0.75 mm to1 mm, and the outer tube has a lumen diameter in the range from 1.5 mmto 3 mm, usually from 1.75 mm to 2 mm. The nature of the shearing bodywill be as generally described above in connection with the methods ofthe present invention.

In the exemplary embodiments, the catheter system will further comprisea drive motor assembly which may be coupled to a proximal portion of theinner catheter shaft to rotate the inner catheter shaft. Optionally, thedrive motor assembly will also be attached to the sheath, where thesheath is held stationary while the inner catheter shaft is rotated.Preferably, the drive motor assembly permits the inner catheter shaft tobe axially translated relative to the sheath so that the shearing bodycan be released from and drawn into the cavity while the inner cathetershaft and sheath remain coupled to the drive motor assembly.

Apparatus according to the present invention further comprise cathetersincluding a catheter shaft having a proximal end and a distal end, and ashearing body disposed near the distal end of the catheter shaft. Theshearing body is configured to engage an interface envelope defined by astent embedded within stenotic material in a blood vessel when theshearing body is displaced therein. Suitable shearing bodies may haveany of the configurations described above in connection with the methodof the present invention. In an exemplary embodiment, the shearing bodycomprises a helical row of radially aligned filaments, typically havinglengths in the range from 1.5 mm to 2 mm. In some cases, the helical rowwill be tapered with longer filaments (1.5 mm to 2 mm) at one end andprogressively shorter filaments in the proximal or distal direction.Alternatively, the shearing body may comprise a brush having bothradially short filament, e.g. having a length in the range from 0.25 mmto 0.5 mm, and radially long filaments, e.g. having lengths in the rangefrom 1 mm to 2 mm.

In yet another specific aspect of the apparatus of the presentinvention, catheter kits comprise a catheter or catheter system andinstructions for use of the catheter system. The catheter will include acatheter shaft having a proximal end and a distal end, and a shearingbody disposed near the distal end of the catheter shaft. Theinstructions for use set forth that the shearing body is to bepercutaneously introduced on one side of a restenosed stent within ablood vessel. The shearing body is then to be translated and rotatedthrough the stent to dislodge stenotic material from an interfaceenvelope defined by the stent. The kit will usually include sterilepackaging, such as a pouch, box, enclosure, or the like, of a typenormally employed for packaging and storing medical devices. Theinstructions for use will typically be included on a separate sheet ofpaper or booklet within the package and/or printed on a portion of thepackage itself.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a blood vessel with portions broken awayto show a stent embedded in a region of restenosis.

FIG. 2 is cross section view taken of along line 2--2 of FIG. 1.

FIG. 3 is a perspective view of a catheter system having a shearing bodyconstructed in accordance with the principles of the present invention.

FIG. 4 is a detailed view of a portion of the catheter system of FIG. 3,shown in cross-section.

FIG. 5 is a detailed view of portion of the catheter system of FIG. 3,shown with the shearing body retracted within a sheath.

FIGS. 6A and 6B illustrate a shearing body, similar to that shown inFIG. 3, further comprising a distal filter element.

FIG. 7 is an enlarged view of a motor drive unit employed by thecatheter system of FIG. 3.

FIG. 8 is a detailed view of a specific construction for a shearing bodyuseful in the catheter system of FIG. 3.

FIG. 9 is an enlarged detailed view of a portion of a filament assemblyuseful for the construction of the shearing body of FIG. 8.

FIG. 10 is an alternative detailed view of a filament assembly usefulfor the construction of a shearing body in accordance with theprinciples of the present invention.

FIG. 11 illustrates an alternative shearing body construction employingboth short and long filaments.

FIG. 12 illustrates another alternative shearing body construction usingnon-linear filaments.

FIG. 13 illustrates a shearing body comprising axially aligned elongateelements.

FIG. 14 a shearing body comprising counter-wound helical elements.

FIG. 15 illustrates a shearing body comprising a helically-woundcontinuous web of material.

FIG. 16 illustrates a shearing body comprising a plurality of axiallyspaced-apart disk elements.

FIG. 17 illustrates a shearing body comprising a perforate solid body.

FIGS. 18A-18E illustrate a method according to the present inventionemploying the catheter of FIG. 3.

FIGS. 19A-19B illustrate an alternative method according to the presentinvention employing a brush-like shearing body and down-stream embolicollection.

FIG. 20 illustrates a kit including a catheter, a package, andinstructions for use according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention provides apparatus and methods for treatingrestenosis which can occur in blood vessels following stent placement.Although stents are themselves intended to inhibit restenosis followinga primary treatment, such as angioplasty or atherectomy, it has beenfound that in a significant number of cases, cell proliferation and/orthrombus formation occur to such an extent that blood flow through thestented lumen is significantly impaired. The result of such restenosisin a previously stented region of a blood vessel, such as a coronary orother artery, is schematically illustrated in FIGS. 1 and 2. As can beseen, a stent S can become embedded in a matrix M of stenotic materialwithin an artery A. The resulting lumen L can thus become veryrestricted. While the stent S is illustrated as a Palmaz-Schatz stent ofthe type available from Johnson and Johnson Interventional Systems, itwill be appreciated that such restenosis can occur in virtually anyconventional stent having opening or interstices in the wall of thestent, including the Gianturco stent, available from Cook, Inc., theWalstent, available from Pfizer, Inc., and the like.

Of particular importance to the present invention, the stent S definesan interface envelope within the matrix M of stenotic material, as bestobserved in FIG. 2. The interface envelope will be generallycylindrical, but will usually display eccentricities resulting from theinitial implantation in a non-cylindrical blood vessel lumen. As thestent will be formed from a material which is significantly harder thanthe stenotic material, usually being composed of stainless steel,tantalum, titanium, nitinol, or other metals, the interface envelopedefines a barrier within the matrix M. The present invention relies onthe interface envelope barrier to define the extent of therecanalization procedure which is performed. In particular, the presentinvention will provide for shearing and/or abrasion of substantially allof the stenotic material from within the interface envelope in a mannerwhich is relatively non-traumatic to the patient and which does notsignificantly damage the stent itself.

The present invention relies on displacement of a shearing body withinthe interface envelope to dislodge the stenotic material from theinterior of the stent S. While the shearing body may take a variety ofspecific forms, it will generally be a compliant structure having awidth (diameter in the case of circular or cylindrical shearing bodies)which is slightly greater than the maximum diameter or width of theinterior surface of the deployed stent. The size of the stent will beknown from the patient records and/or can be determined by knowndiagnostic techniques, such as fluoroscopy, intravascular ultrasound(IVUS), or the like. The size of the shearing body can then be chosen tobe slightly greater than the interior diameter or width of the stent,typically being at least 1% greater in width, preferably being from 1%to 25% greater, more preferably being from 2% to 20% greater, and stillmore preferably being from 5% to 15% greater in width.

The shearing body will comprise an exterior surface which, whendisplaced within the stented region of the blood vessel, will act toshear or abrade the stenotic material from the interface envelopedefined by the stent. The shearing body may comprise a solid, expansiblebody, e.g. a sponge-like mass optionally embedded with abrasiveparticles or other elements over its exterior surface, but will moreusually comprise a series of discontinuous elements, such as brushfilaments, fabric disks, a helically wound row of fabric or othermaterials, expansible cages, and the like. Specific examples of each ofthese constructions will be described in greater detail below.

The shearing body will be displaced within the stented region of theblood vessel. Such displacement will comprise at least axialtranslation, i.e. motion along the axis of the blood vessel, orrotation, i.e. rotation about the axis of the blood vessel. Moreusually, the displacement will comprise simultaneous rotation and axialtranslation so that the surface of the shearing body is continuouslyswept about the inner periphery of the interface envelope as theshearing body is axially advanced through the matrix of stenoticmaterial. It will be appreciated that displacement of the shearing bodymay also comprise axial and/or rotational oscillation. Frequently, suchaxial and rotational oscillation may be superimposed over thetranslation and rotation of the shearing body through the stenoticmaterial.

The compliant nature of the shearing body may be achieved in a varietyof ways. In the case of the brush-like shearing bodies, the individualfilaments or other elements of the brush will themselves be flexible andcapable of bending or folding in order to compress as the shearing bodyis introduced into the stented region of the blood vessel. Similarly, afabric or membrane material used to form a helical row or axiallyspaced-apart disks will be sufficiently flexible so that it can becompressed to accommodate passage through the stented region of theblood vessel. Cage structures will usually be resilient and constructedso that they can spring open and closed so that they will radiallycompress as they enter the stented region. Sponges and other continuousbody structures will be composed of or fabricated from materials whichare inherently sufficiently compressible so that they may be compressedor constricted to accommodate the reduced diameter of the stentedregion. A variety of other structures will also be capable of providingthis degree of compliance and compressibility. It will be appreciated,however, that all of these structures will also possess a sufficientresilience so that they will radially expand as the stenotic material isremoved. It is desirable that the shearing body be able to assume awidth or diameter which is sufficiently large so that it will engage theinterior surface of the stent (i.e. the interface envelope defined bythe stent) as the shearing body is displaced therein. In this way, theshearing body will be able to sweep the interior surface of the stent torecanalize the stented region within the blood vessel.

Optionally, the shearing body may have an adjustable width or diameter.That is, the catheter systems of the present invention may provide theuser with the ability to selectively adjust a radial dimension of theshearing body, typically the diameter or width. As illustrated in moredetail below, expansible cages may be provided where the axial dimensionmay be adjusted in order to expand or contract the radial dimension. Theuse of such radially adjustable shearing bodies may be advantageoussince the shearing body may be introduced in a narrow widthconfiguration and subsequently expanded as the shearing body is rotatedor otherwise displaced in order to incrementally shear or abrade thestenotic material from the lumen within the stented region of the bloodvessel. For example, the width of the shearing body can be graduallyincreased until contact with the stent is detected. Such detection maybe achieved in a variety of ways, including expansion to a preselecteddiameter (based on a known or measured width of the stent), detection ofresistance to further expansion, and/or detection of a change inelectrical (e.g. resistance, inductance and/or capacitance) or othercharacteristics based on contact with the stent.

The shearing or abrasive action provided by the shearing body may besolely mechanical or may be augmented by the application of heat,ultrasonic energy, radiofrequency energy, or the like. For example, whenthe shearing body comprises a metallic cage, as described in greaterdetail below, it will be possible to apply monopolar or bipolarradiofrequency energy in order to effect cutting and/or cauterizing ofthe stenotic material which is being removed. Similarly, it would bepossible to enhance the mechanical displacement of the shearing body bysuperimposing ultrasonic vibrational energy.

The shearing body will preferably comprise intersticies or internalvoids which permit entrapment of the stenotic material as it isdislodged from the interior of the stented region of the blood vessel.The nature of the intersticies or voids may vary widely, and the extentof such variation will be apparent from examination of the particularshearing bodies illustrated below. For example, brush elements willinclude rather large void regions between individual filaments of thebrush. Helically wound filaments and webs will include spaces betweenthe adjacent turns of the helix. Similarly, multiple disk elements willinclude spaces between each successive disk. Cages and basket structureswill include significant interior volume for collecting the dislodgedstenotic material, and sponge-like structures will also includesignificant internal void volumes which can collect the stenoticmaterial.

The present invention is not limited to shearing bodies having suchintersticies or void volumes. For example, the inflatable balloons andother structures described previously may not have such void volumes(although balloons can be configured in helices and spirals which willhave void volumes). Similarly, shearing bodies which comprise a singledisk or other single, discrete elements may not have void volumes. Insuch cases, it will usually be desirable to provide an emboli collectionability apart from the shearing body itself.

The catheter systems of the present invention, regardless of the natureof the shearing body, will usually be provided with an ability tocollect and remove emboli which are dislodged by the shearing body. Inan illustrated embodiment below, the collection ability it provided byan aspiration catheter which is coaxially mounted over a catheter shaftwhich carries the shearing body. In an alternative embodiment below, thecollection is provided by a separate emboli aspiration catheter whichmay be separately introduced to the patient, e.g. through a separatefemoral access tract. A variety of other specific emboli collectiondevices and methods will be suitable for use with the present invention.

The shearing bodies described thus far are intended for percutaneous,intravascular introduction using a suitable catheter or catheter system.The shearing body will usually be carried at the distal end of an innercatheter shaft having a relatively low profile, typically with adiameter in the range from 0.2 mm to 1 mm. The inner catheter shaft willusually have an internal lumen suitable for receiving a guidewire, andwill have sufficient column strength and torsional rigidity to permitboth axial translation and rotation of the shearing body from theproximal end of the shaft. Thus, the inner catheter shaft should besuitable to act as a drive cable for the shearing body. The innercatheter shaft may be a multi-filar and/or counterwound coil, a braid-or coil-reinforced polymeric tube, e.g. composed of polyimide, polyamide(nylon), or may be a hypotube or other flexible metallic structure. Insome cases, it may be desirable to combine two or more of suchstructures in a single drive cable. For example, the proximal end of adrive cable may be formed from a relatively less-flexible structure,such as a hypotube, while the distal end is formed from a more flexiblestructure such as a multi-filar and/or counterwound coil. Specificconstructions for such drive cables are well known in the art. See, forexample U.S. Pat. No. 5,108,411, the full disclosure of which isincorporated herein by reference. The length of the inner catheter shaftwill be sufficient to permit introduction of the shearing body to atarget location within the vasculature. For introduction to the coronaryarteries from a femoral access tract in the patient's groin, a length inthe range from 90 cm to 150 cm, will typically be sufficient.

Catheter systems according to the present invention may further comprisea sheath for covering the shearing body during introduction. In the caseof radially compressible (self-expanding) shearing bodies, the sheathmay also act as a radial constraint, where retraction of the sheathpermits radial expansion of the shearing body. The sheath will usuallycomprise a thin-walled tubular component which is axially slidablerelative to the inner catheter shaft to permit retraction and deploymentof the shearing body and will define a cavity which receives theshearing body. As described in more detail below, both the sheath andthe inner catheter shaft will often be connected at their proximal endsto a drive motor which anchors to the sheath and permits rotation and/oraxial translation of the inner catheter shaft. The sheath will usuallybe composed of a polymeric material such as a polyethylene,polyethyleneterephthalate, polypropylene, polyurethane, polyimide,polyamide (nylon), polyvinylchloride, or copolymers and mixturesthereof, or the like, and may readily be fabricated by conventionalextrusion techniques. The sheath will typically have a length which issomewhat less than that of the inner catheter shaft, typically beingfrom 5 cm to 50 cm shorter.

In addition to the inner catheter shaft and sheath, catheter systemsaccording to the present invention may also include an outer cathetertube which is coaxially received over the sheath. Thus, the outercatheter tube will have a lumen diameter which is slightly greater thanthe sheath. Typically the sheath will have an outer diameter in therange from 0.5 mm to 1.5 mm, and the outer catheter tube will have alumen diameter in the range from 1.5 mm to 3 mm. In a preferredconfiguration of the present invention, the outer catheter tube willinclude a proximal hub having an aspiration port. The hub will permithemostatic attachment to the exterior of the sheath, and an annularlumen between the interior of the outer catheter tube and exterior ofthe sheath will be created. Such annular lumen will be useful foraspiration of emboli and other debris created during the recanalizationprocedures of the present invention. In particular, a vacuum source canbe connected to the aspiration port, permitting aspiration of the embolithrough the annular lumen.

Apparatus according to the present invention will further comprisecatheter kits. Such kits will include any of the catheters and cathetersystems described above in combination with instructions for use (IFU)setting forth the methods of the present invention. The catheter andinstructions for use will typically be packaged together in conventionalsterile packaging, such as a pouch, tray, box, or the like. Theinstructions for use will most commonly be printed on a separate sheetor in a separate booklet, but in some cases may be incorporated intoother components of the packaging.

Methods according to the present invention are intended to position theshearing body adjacent to or within a stented region of the patient'svasculature. The shearing body is then deployed and displaced, generallyas described above, in order to dislodge stenotic material from withinthe stenosed region. The methods will preferably further comprisecollection and removal of the dislodged stenotic material from thevasculature. The shearing body will be deployed in a radially collapsedor constrained configuration and/or will be expanded to a width ordiameter which is slightly larger than the stent to be treated, and willthereafter be displaced within and through the stented region in orderto dislodge the stenotic material. In a first illustrated embodiment,the catheter system is deployed on one side of the stented region andthe shearing body distally advanced to the opposite side of the stentedregion while in a radially constrained configuration. The shearing bodyis then radially expanded and drawn back toward the catheter in order todislodge the stenotic material. Aspiration is provided through thecatheter in order to collect and remove emboli and other debris. Thismethod relies on the use of a single catheter, thus reducing trauma tothe patient.

In a second illustrated embodiment, the two catheters are separatelyintroduced to opposite sides of the stented region. The first of thesecatheters is used to deploy and advance the shearing body through thestented region in order to dislodge material. The second catheter isused to collect and remove the emboli and other debris which has beendislodged by the shearing body. It will be appreciated, of course, thatin some cases it may be desirable to aspirate the debris through bothcatheters. It may be further desirable to provide filters, balloons, andother barriers to help isolate the region being treated and prevent therelease of emboli during the procedure.

Referring now to FIGS. 3-5, a first exemplary catheter systemconstructed in accordance with the principles of the present inventionwill be described. The catheter system 10 includes an inner cathetershaft 12, a tubular sheath 14 slidably received over the inner cathetershaft, and optionally an outer catheter tube 16 coaxially and slidablyreceived over the tubular sheath. For some clinical applications, thecatheter assembly comprising the inner catheter shaft 12, tubular sheath14, and outer catheter tube 16 may be introduced through a guidecatheter 18. The guide catheter 18 is useful for directing the catheterassembly to a particular target location within the patient'svasculature. For example, a coronary guide catheter having a curveddistal end can be used for selecting a particular coronary ostium tointroduce the catheter assembly to the right or left coronary artery.The guide catheter 18 may also provide support for pushing, rotating andmaneuvering the catheter assembly. Use of the guide catheter 18,however, may not be necessary for all applications. Moreover, it willoften be possible to use conventional coronary guide catheters in themethods and systems of the present invention.

Each of the inner catheter shaft 12, tubular sheath 14, outer cathetertube 16, and guide catheter 18 will have a distal end and a proximalend. Shearing body 20 is disposed at the distal end of the innercatheter shaft 12, and drive motor assembly 22 is attached to theproximal end of the inner catheter shaft 12. In general, the distal endof each of the catheter system components will be that which enters intothe patient's vasculature while the proximal end is that which remainsoutside of the vasculature. Access to the vasculature will usually bethrough the femoral artery in the patient's groin or through the radialor brachial artery in the patient's arm using a conventional accesssheath having a hemostasis valve (not illustrated). Intravascular accessto the coronary arteries or other target locations will be provided overa conventional guidewire GW. The outer catheter tube 16 will include ahub 24 at its proximal end, and the hub includes both the hemostasisport 26 and an aspiration port 28. The guide catheter 18 will include aconventional hemostasis port 30 at its proximal end.

The shearing body 20 comprises a brush structure including a helical rowof filaments 34 arranged in a spiral pattern. A small-diameter end ofthe spiral is positioned proximally and the large-diameter end of thespiral is positioned distally. The diameter of the small-diameter end isapproximately equal to that of the inner catheter shaft 12, i.e. in therange from 0.2 mm to 1 mm, while the diameter of the large-diameter endis in the range from 3 mm to 5 mm, with the particular diameter chosenbased on the diameter of the stent to be treated. The individualfilaments may be composed of a polymeric material or metal, as describedabove. The filaments will usually have a diameter in the range from 0.05mm to 0.15 mm, typically from 0.07 mm to 0.13 mm, with a lengthdepending on their axial position within the shearing body 20. The totallength of the shearing body in the axial direction will typically be inthe range from 5 mm to 40 mm.

As best observed in FIGS. 4 and 5, the helical rows 34 of the shearingbody are radially collapsed when drawn proximally into the sheath 14(FIG. 5). When distally advanced, the rows 34 will radially expand dueto their own resiliency. In a preferred construction, the filaments ofhelical rows 34 are attached at their radially inward ends to a spirallywound filament 36. The filament 36 is wound about the exterior of theinner catheter shaft 12, and will usually be an extension or part of ahelical reinforcement coil 38 which extends proximally over a portion orall of the inner catheter shaft. An annular aspiration lumen 40 definedbetween the exterior surface of sheath 14 and the interior luminalsurface of outer catheter tube 16 can be seen in FIG. 4.

A modification of the shearing body 20 is illustrated in FIGS. 6A and6B. Shearing body 20A includes successive helical turns 34 of thetapered shearing body, identical to shearing body 20 as shown in FIG. 3.In addition, a filter assembly 50 is attached near the distal end of theinner catheter shaft 12. Filter assembly 50 comprises a series of fouraxially adjacent filter elements 52. The filter elements 52 may becomposed of any of the materials listed above suitable for filaments 34.The filter elements 52, however, will generally have a greater densitywhich will prevent passage of the emboli through the filter assembly 50.

FIG. 6B is an end view of a single filter element 52 of the filterassembly 50. Each filter element 52 comprises a multiplicity of fibers53 which extend generally radially from the inner catheter shaft 12. Inthe illustrated embodiment, the individual fibers are shown to be kinkedand arranged in a randomly overlapping pattern in order to define afiltering structure with a "pore size" sufficiently small to entraplarger emboli particles, typically those above 0.15 mm in size, yetsufficiently open to permit adequate blood flow during the procedure toavoid ischemia. The individual fibers 53, of course, could be arrangedin other patterns, such as serpentine, helical, spiral, and the like inorder to provide a desired density for the filter elements 52.

The filter assembly 50 is shown to be directly mounted on the innercatheter shaft 12 at a point distally of the shearing body 20A.Optionally, the filter assembly 50 may be mounted to freely rotate onthe inner catheter shaft so that the filter assembly itself does notrotate during rotation of the shearing body 20A. Alternatively, thefilter assembly 50 or an equivalent structure could be mounted on aseparate filter support wire (not shown) which extends through theguidewire lumen of the inner catheter shaft 12.

In order to provide a filter element 52 having a relatively uniformporosity in the radial direction, the degree of kinking or bending ofthe individual fibers 53 can increase in the radially outward direction.In this way, the density provided by the randomly overlapping individualfibers 53 will remain generally uniform over the entire surface of thefilter element 52. When multiple filter elements 52 are arranged in aspace-part manner, as shown in FIG. 6A, the individual filter elementsmay have differing porosities in order to provide a porosity gradient inthe axial direction. In this way, the filter assembly can moreeffectively capture small emboli without plugging because the largeemboli will be captured by the upstream filter elements 52 with a largerpore size.

The filter assembly 50 will be sufficiently flexible so that it may becollapsed for both delivery from sheath 14 and the recapture withinouter catheter tube 16. In addition to the filament assemblies describedabove, the filter assemblies could also be formed from woven, braided,or knit materials, or non-woven porous membranes and fabrics.

The drive motor assembly 22 is best illustrated in FIG. 7. Assembly 22comprises a motor 60 having a spindle 62 which engages and drives asleeve assembly 64. The inner catheter shaft 12 (not shown in FIG. 7) isreceived through a passage 66 in the distal end of the drive motorassembly 22 and captured in the sleeve assembly 64. The inner cathetershaft 12 will continue through the proximal portion of passage 66 and isrotatably received in an O-ring 61. A guidewire passing through theinner catheter shaft 12 may pass out through a hemostatic seal 63 at theproximal end of the passage 66. A port 65 is optionally provided on thedrive motor assembly 22 proximally of the O-ring 61 in order to aspirateand/or perfuse fluids through the inner lumen of inner catheter shaft12, particularly when the guidewire is withdrawn therefrom.

The sleeve assembly 64 comprises a compression fitting 67 which may beengaged against an exterior surface of inner catheter shaft 12 bytightening on knob 69 which is threadably attached to the portion of theassembly which engages spindle 62. In this way, the sleeve assembly canbe tightened on to the inner catheter shaft 12 and thereafter driven bymotor 60.

The inner catheter shaft 12 will be axially advanced and retractedrelative to the outer catheter tube 16 by moving the drive motorassembly 22 relative to the proximal hub 24 of the outer catheter tube.Usually, this will be done manually. Optionally, mechanical assembliesmay be provided in order to anchor the proximal end of the outercatheter tube 16 and translate the drive motor relative to the hub andin order to advance and retract the shearing body 20.

Usually, the sheath 14 will be removed prior to rotating the innercatheter shaft 12 with the drive motor assembly 20. For example, thesheath 14 may be a splittable sheath which can be pulled apart andaxially split as it is withdrawn from outer catheter tube 16.Alternatively, as illustrated in FIG. 3, the sheath 14 may be proximallyretracted into a cavity 80 formed coaxially with the passage 66. In thisway, the sheath will be held stationary (immobilized) as the innercatheter shaft 12 is rotated by the drive motor assembly 22. As afurther alternative, the sheath 14 may be removed prior to attaching thedrive motor assembly. As a still further alternative, the sheath 14could be removed together with the guidewire through the hemostasis seal63. Generally, however, removing the sheath 14 entirely will bepreferred since it will increase the available area of the annularaspiration lumen defined between the exterior of the inner cathetershaft 12 and the interior of the outer catheter tube 16.

Referring now to FIGS. 8 and 9, a particular method for fabricating ashearing body according to the present invention will be described. Theinner catheter shaft 12 is wrapped with a spiral filament 36 generallyas described above. Radial filaments 90 are provided in the form ofU-shaped elements which may be placed over the filament 36 as best seenin FIG. 9. The filament 36 is then wound around the shaft 12 to providea helical row of filaments. The spiral filament 36 extends proximallydown the shaft 12 with successive turns becoming progressively closer.Eventually, the coil 36 is intertwined with turns of a separate helicalreinforcement coil 92 which extends proximally down the shaft 12 to forma multi-filar drive cable.

A second alternative for forming brush filaments suitable for helicallywrapping around the inner catheter shaft 12 is illustrated in FIG. 10.There, a flat sheet of material may be machined, photochemically etched,or otherwise patterned to have an array of comb-like elements 96extending from a base 98. The base 98 may then be wrapped around andattached to the inner catheter shaft 12.

Referring now to FIG. 11, an alternative embodiment of a shearing body100 which may be attached to the distal end of inner catheter shaft 12as illustrated. The shearing body 100 includes a plurality of both shortelements 102 and long elements 104. The shorter elements typically havea length in the range from 0.25 mm to 0.5 mm and the long filaments havea length in the range from 1 mm to 2 mm. Preferably, the long elements104 will all be curved or deflected near their radially outward ends topresent axially aligned region for sweeping against the interfaceenvelope as the shearing body 100 is rotated within the stented regionof a blood vessel (optionally having a hook-like configuration to helpentrap the dislodged stenotic material). The filaments 102 and 104 maybe composed of the same or different materials, including any of thematerials described above for use in the previous embodiments. Theshearing body 100 is shown with a generally cylindrical (uniformdiameter) configuration, but could readily be adapted to have a taperedconfiguration as previously described.

FIG. 12, is an end view of another shearing body 110 comprisinggenerally radially aligned brush filaments. The brush filaments 112 areshown to be kinked, similar to the configuration of the filter elements52 in FIG. 6B, resulting in a highly irregular network which isparticularly efficient for entrapping thrombus dislodged by the shearingbody 10. It will be appreciated that the kinked filaments of 112 couldbe combined with any of the other filaments of the other embodiments toprovide brush structures having different regions with different removaland entrapment characteristics.

A variety of other shearing body configurations are illustrated in FIGS.13-17. In FIG. 13, a cage-type shearing body 120 is mounted at thedistal end of inner catheter shaft 12. The cage 120 comprises aplurality of axially aligned resilient elements 122, and each of theindividual elements is shaped so that the shearing body 120 has agenerally cylindrical, large-diameter configuration when unconstrained.The elements 122 can be round filaments, ribbon filaments, or have avariety of other cross-sections, and be formed from virtually any of thepolymeric materials and metals described above for use as brushfilaments. The elements are attached to the inner catheter shaft 12 by adistal ring 124 and a proximal ring 126. Usually, the distal ring 124will be fixed to the shaft 12, while the proximal ring 126 will be freeto axially translate over the shaft as the elements 122 are radiallycollapsed or expanded. It will be appreciated, of course, that a rod orshaft (not shown) could be attached to ring 26 so that the elements 122could be selectively expanded or contracted by axial motion of the rodor shaft. In this way, the diameter of shearing body 120 could beselectively adjusted from the proximal end of the shaft.

Shearing body 130 illustrated in FIG. 14 is similar to the cagestructure of shearing body 20. Instead of axial elements 122, however,shearing body 130 comprises counter-wound helical elements 132 and 134.The helical elements 132 and 134 may comprise round filaments, ribbonfilaments, or the like, and may be composed of virtually any of thepolymeric materials and metals described above for use as brushfilaments. The helical elements are attached in a distal ring 136 andproximal 138. The proximal ring 138 may be free to slide over the shaft12 and may be optionally be attached to a rod, sleeve, or other meansfor axially translating the ring in order to adjust the radius of theshearing body 130.

FIG. 15 illustrates a shearing body 140 comprising a continuous web ofmaterial arranged in a helical pattern. The material may be a fabric,membrane, or other continuous structure of a compliant or flexiblenature. For example, the continuous web of material may be formed frompolyamides (nylon), polyimides, polyethylenes,polyethyleneterephthalates, polypropylenes, latex rubbers, siliconerubbers, and mixtures and combinations thereof. The continuous web 142will be helically wrapped in a manner analogous to the brush filamentsdescribed previously. As shown, the helical web is in a cylindricalarrangement. The web, of course, could be arranged in a tapered patternas previously discussed.

Shearing body 150 in FIG. 16 comprises a plurality of axially-spacedapart disks 152. The disks are composed of a fabric or membrane,preferably polyamides (nylon), polyimides, polyethylenes,polyethyleneterephthalates, polypropylenes, latex rubbers, siliconerubbers, and mixtures and combinations thereof. The disks defineinterstices therebetween for entrapping stenotic material which has beendislodged from within the stent. Disks are shown in a cylindricalarrangement, but could readily be adapted to a tapered configuration.

Shearing body 160 illustrated in FIG. 16 comprises a solid expansiblebody, typically in a sponge-like configuration, such as open cellplastic foams, reticulated fibrous networks, natural sponge material,and the like. The plastic foams are preferably formed from polyurethaneor polyethylene, while the reticulated fibrous networks may be formedfrom any of the polymeric fiber materials listed above for use as brushfilaments. Abrasive particles or other elements may be incorporated inthe exterior surface of the body 162, and voids 164 within the body aresuitable for entrapping stenotic materials which has been dislodged fromwithin the stented region.

Referring now to FIGS. 18A-18E use of the catheter system 10 forremoving stenotic material M from within a stent S and a blood vessel BVwill be described. The catheter system is introduced in a conventionalpercutaneous intravascular manner so that the distal end of outercatheter tube 16 is positioned adjacent to one side of the restenosedarea having stent S therein, as illustrated in FIG. 18A. Generally, thecatheter system 10 will be operated with the guidewire GW in place inorder to permit catheter exchange and/or advance of the catheter systemor components thereof for treating other lesions. If desired, however,the guidewire GW may be removed after a lesion has been crossed with theshearing body. Sheath 14 is then distally extended over guidewire GWuntil its distal end lies beyond the stented region, as shown in FIG.18B. The sheath 14 is then withdrawn (and optionally removed from thecatheter system 10) and/or the inner catheter tube 12 extended so thatthe shearing body 20 lies beyond the stented region, as illustrated inFIG. 18C. The shearing body is then rotated, typically at a rotationalspeed in the range from 10 rpm to 10,000 rpm, usually from 60 rpm to6000 rpm, and axially drawn in the proximal direction so that it passesthrough the stenotic material M, as illustrated in FIG. 18D. Thestenotic material is sheared from within the interface envelope by stentS with the resulting particulate material being captured within adjacentturns of the filaments of the shearing body 20, also as illustrated inFIG. 18D. Aspiration is applied through the port 28 so that some of theparticles are drawn into the distal end of outer catheter tube 16. Theshearing body continues to be drawn in the proximal direction, withaspiration applied, until the shearing body is recaptured within thesheath 16, leaving the stented region recanalized and substantially freefrom stenotic material with the stent S as shown in FIG. 18E. Byrotating the helical shearing body 20 in the direction shown by thearrow in FIG. 18D, the helical row acts to "pump" stenotic material andother debris toward the distal end of the outer catheter tube 16. Bycombining such pumping action with aspiration within the outer cathetertube 16, efficient collection of the stenotic material and other debriscan be accomplished. Such pumping can be provided by any of the helicalshearing body arrangements described herein.

An alternative method for removing stenotic material M from within astent S in a blood vessel BV is shown in FIGS. 19A and 19B. The cathetersheath 16 is deployed adjacent one side of the stenotic material M, asshown in FIG. 19A, and a brush-like shearing body 200 is advanceddistally from the distal end thereof. Brush 200 is rotated and axiallyadvanced (in the distal direction) through the stenotic material M. Asecond catheter 210 is positioned on the opposite side of stenoticmaterial M and comprises an expandable skirt 212 which assists incapturing emboli released during the recanalization process. The skirt212 may conveniently comprise a perforate structure, such as a wiremesh, so that blood flow can be maintained during the procedure.Aspiration will be provided through the catheter 210 to enhancecollection of emboli. Shown in FIG. 19B, the brush 200 continues to berotated and distally advanced through the stenotic material M, until theregion is fully recanalized.

Referring now to FIG. 20, a catheter kit according to present inventioncomprises a catheter or catheter system 300, often mounted on a board302, instructions for use (IFU), and a pouch or other conventionalpackage 304. The instructions for use IFU are typically part of aseparate sheet or booklet which, together with the catheter 300, ispackaged within the pouch or other packaging material 304. The packagingwill preferably be sterile or sterilizable. The instructions for use IFUwill set forth methods steps comprising the method(s) as describedabove.

While the above is a complete description of the preferred embodimentsof the invention, various alternatives, modifications, and equivalentsmay be used. Therefore, the above description should not be taken aslimiting the scope of the invention which is defined by the appendedclaims.

What is claimed is:
 1. A catheter system comprising:an inner cathetershaft having a proximal end and a distal end; a radially compressiblecompliant shearing body disposed near the distal end of the innercatheter shaft, wherein the shearing body has a first end and a secondend and wherein the shearing body is tapered so that one end is largerthan the other; and a sheath having a proximal end, a distal end, and acavity near the distal end, wherein the inner catheter is slidablycoupled to the sheath so that the compliant shearing body can beradially constrained within and released from the cavity.
 2. A cathetersystem as in claim 1, further comprising an outer catheter tube having aproximal end, a distal end, and a lumen therethrough, wherein the outercatheter tube comprises a hub at its proximal end, said hub having anaspiration port.
 3. A catheter system as in claim 1, wherein the innercatheter shaft has a guidewire lumen extending from the proximal end tothe distal end.
 4. A catheter system as in claim 2, wherein the innercatheter shaft has a diameter in the range from 0.2 mm to 1 mm, theshearing body has a maximum width when radially unconstrained in therange of 2 mm to 5 mm, the sheath cavity has a diameter in the rangefrom 0.75 mm to 2 mm, and the outer catheter tube has a lumen diameterin the range from 1.5 mm to 3 mm.
 5. A catheter system as in claim 1,wherein at least a portion of the shearing body has a generally roundcross-section.
 6. A catheter system as in claim 1, wherein at least aportion of the shearing body has a polygonal cross-section.
 7. Acatheter system as in claim 1, wherein the shearing body comprises anaxially elongate surface.
 8. A catheter system as in claim 1, whereinthe shearing body comprises a helical row.
 9. A catheter system as inclaim 8, wherein the helical row comprises a helically aligned radiallyoriented filaments.
 10. A catheter system as in claim 8, wherein thehelical row comprises a continuous web of material.
 11. A cathetersystem as in claim 1, wherein the shearing body comprises a brush.
 12. Acatheter system as in claim 1, wherein the shearing body comprises acage.
 13. A catheter system as in claim 1, wherein the shearing body iscompliant with an unconstrained width greater than the width of thesheath cavity so that the shearing body may be radially constrainedwithin said cavity.
 14. A catheter system as in claim 1, wherein theshearing body may be expanded by application of a compressive force inthe axial direction, further comprising means for applying an axiallycompressive force to the shearing body.
 15. A catheter system as inclaim 1, further comprising a drive motor assembly which may be coupledto a proximal portion of the inner catheter shaft to rotate the innercatheter shaft.
 16. A catheter system as in claim 15, wherein the drivemotor assembly may also be attached to a proximal portion of the sheath,wherein the sheath is held stationary while the inner catheter shaft isrotated therein.
 17. A catheter system as in claim 16, wherein the drivemotor assembly permits the inner catheter shaft to be axially translatedrelative to the sheath so that the compliant shearing body can bereleased from and drawn into the cavity while the inner catheter shaftand sheath remain coupled to the drive motor assembly.
 18. A cathetersystem comprising:an inner catheter shaft having a proximal end and adistal end; a radially compressible helical row of radially orientedfilaments disposed near the distal end of the inner catheter shaft; anda sheath having a proximal end, a distal end, and a cavity near thedistal end, wherein the inner catheter is slidably coupled to the sheathso that the compliant shearing body can be radially constrained withinand released from the cavity.
 19. A catheter system as in claim 18,further comprising an outer catheter tube having a proximal end, adistal end, and a lumen therethrough, wherein the outer catheter tubecomprises a hub at its proximal end, said hub having an aspiration port.20. A catheter system as in claim 18, wherein the inner catheter shafthas a guidewire lumen extending from the proximal end to the distal end.21. A catheter system as in claim 20, wherein the inner catheter shafthas a diameter in the range from 0.2 mm to 1 mm, the helical row has amaximum width when radially unconstrained in the range of 2 mm to 5 mm,the sheath cavity has a diameter in the range from 0.75 mm to 2 mm, andthe outer catheter tube has a lumen diameter in the range from 1.5 mm to3 mm.
 22. A catheter system as in claim 18, wherein at least a portionof the helical row has a generally round cross-section.
 23. A cathetersystem as in claim 18, wherein at least a portion of the helical row hasa polygonal cross-section.
 24. A catheter system as in claim 18, whereinthe helical row is tapered at at least one end, with said one end havinga smaller width than other portions of the helical row.
 25. A cathetersystem as in claim 18, wherein the helical row is compliant with anunconstrained width greater than the width of the sheath cavity so thatthe shearing body may be radially constrained within said cavity.
 26. Acatheter system as in claim 18, further comprising a drive motorassembly which may be coupled to a proximal portion of the innercatheter shaft to rotate the inner catheter shaft.
 27. A catheter systemas in claim 26, wherein the drive motor assembly may also be attached toa proximal portion of the sheath, wherein the sheath is held stationarywhile the inner catheter shaft is rotated therein.
 28. A catheter systemas in claim 27, wherein the drive motor assembly permits the innercatheter shaft to be axially translated relative to the sheath so thatthe compliant shearing body can be released from and drawn into thecavity while the inner catheter shaft and sheath remain coupled to thedrive motor assembly.